1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer-readable recording medium storing therein an image processing program for detecting a lesion area from in-vivo images that are captured images of the inside of a body cavity.
2. Description of the Related Art
In recent years, capsule endoscopes have been developed as medical equipments for capturing images of the inside of a body cavity of a subject. The capsule endoscope is swallowed from a mouth, captures images of the inside of a body cavity (in-vivo images) at a predetermined imaging rate while moving through digestive tracts with peristaltic movement or the like, transmits the captured in-vivo images to a receiving device outside the body, and is excreted out of the body in the end. The number of in-vivo images to be captured is approximately represented by the imaging rate (about 2 to 4 frames/sec)×in-vivo residence time of the capsule endoscope (about 8 hours=8×60×60 sec), which results in a large number of images such as more than several tens of thousands of images. Observers such as doctors spend a lot of time to check the large number of in-vivo images transmitted to the receiving device outside the body for identifying a lesion area, by using diagnostic workstations or the like. Therefore, a technology for improving the efficiency of observation operations of the in-vivo images has been strongly desired.
As a technology for solving such a problem, a technology for detecting an abnormality observed area (lesion area) from in-vivo images has been proposed. For example, Japanese Laid-open Patent Publication No. 2005-192880 discloses a technology in which clustering is performed by mapping either a pixel value of each pixel of an in-vivo image or an averaged pixel value to a feature space based on color information, and data whose Euclidean distance from a cluster of a normal mucous-membrane area is equal to or larger than a predetermined value is detected as a lesion area.